Principles of Good Interface and Screen Design 255

Step 3: Principles of Good Interface and Screen Design 255

Results presentation: — Present a textual listing that is

• Concise. • Ten to 50 returns in length. • Arrayed in order of relevance. • Clear. • Easily scannable.

Permit the user to — Modify the result set sequencing. — Cluster the result set by an attribute or value.

For multipage listings, make obvious the link to the next search result page. For results with only one item, immediately present the result page.

Present polite and useful messages.

Goal. In presenting meaningful results, the objective is to provide exactly the infor-

mation or answer the user is looking for. Presenting information or data in great quantities will test the user’s patience and likely “hide the tree in the forest.” Presenting irrelevant results often leads to abandonment of the search. To speed the search results review process, present information in a language and format that is easy to understand and use.

Criteria summary. Present a summary of the search criteria with the search results. Never assume that the user will remember what the search parameters were. Explanatory messages. Provide meaningful messages explaining search outcomes

that aid progressive refinement. Include how many items compose the search result set.

Results set presentation. Result listings should be concise, arrayed in order of rele-

vance, clear, and easily scannable. A concise listing is one that displays the least pos- sible amount of return descriptive information for determining that a match meets the user’s search needs. Presenting 10 to 50 search returns per results page opti- mizes both performance and preference (Bernard et al., 2002a). This study did find, however, that a listing of 50 returns resulted in faster scanning and information location, and was preferred by users. Eysenbach & Kohler (2002) report that users typically peruse only the first page of search results, 93 percent of the links visited being within the first 10 results. Joachims et al. (2005) found that 42 percent of the users selected the top item in a relevance order listing (see below). When the num- ber one and two items were (without telling the participants) swapped in position (the second item in the most relevant listing now being placed on top), the new top item was still selected 34 percent of the time. Nielsen (2005d) concludes this may have occurred because 1) search engines are good at judging relevancy and almost always place the best on top, 2) users assume the search engine places the best on top, or 3) people tend to select the top item because it is first on the list. He suggests the answer is a combination of all three factors.

256 Part 2: The User Interface Design Process

Present the results in the most useful way possible. A list that is relevance- ordered places exact or best matches first and follows with those less close. A relevance-ordered list may also be sorted by a criterion reflecting the users’ need — alphabetically, chronologically, by date, and so forth.

A clear listing provides enough information for the user to determine whether to proceed. Textual listings are usually much clearer than graphical listings. Consider graphical listings, such as maps, however, if the information will be more clearly presented in a graphical format. While being concise, a one to three word description, in most cases, will not provide the necessary clarity. URLs should not be presented because they tend to confuse more than help. Page upload dates should be presented only if they are of relevance to the searching user. A news site date, for example, is usually important to the user. For most other kinds of sites, including the date would not be relevant.

Present an easily scannable results listing. A vertical array with highlighted keywords is best. Allow the user to modify the result set by changing its sequenc- ing; from alphabetical to chronological, for example. Allow the user to cluster the result set by an attribute or value, or by presented topics. For multiple-page list- ings, the link to the next search page should be clearly presented at the end of the listing currently being displayed. This link should not be displayed when no more listing pages follow. For results that find only one item to link to, immedi- ately present the item page instead of presenting a one-item listing.

Messages. If no items are found to present in a listing, provide an informational message telling so. If search parameters are incorrect, politely provide advice telling how to correct the problem.